i just purchased a 1.8 dual g5 as well
came with 1 gb ram , nvidia 6800gt , 500gb hd
updated ram to 3 gig
250 gig ssd
cloned drive with cc cloner no issues
i love these older macs , i have done a hack in these cases
but im going to leave this one working as is
turns out i had an older clover on the usb?
odd because i used the latest unibeast installer
the fix was to install the latest clover on the hd reboot to installer
have a snack
install web driver(nvidia)
just need to address the audio(realtek 892)...
I'm assuming u have a working hack.
i used the boot files supplied on tonys first post to build usb drive..
then adjusted my setting to my build , i use mac pro 5.1
is your (current) OS X install booting?